In recent years, pursuant to the expansion and development of the information-oriented society, numerous computer systems are in existence. And many of these computer systems are mutually connected via a communication network such as the internet, and exchange information and perform information processing by coordinating with each other.
These types of computer systems are under information attack known as cyber attack, and this trend is getting even worse. Thus, computer systems are equipped with a defense mechanism against unauthorized or malicious access resulting from computer viruses and Dos attacks (Denial of Service attacks). Anti-virus software against computer viruses is one such example. Furthermore, computer systems are configured to additionally prevent the diffusion and propagation of unauthorized events.
For example, Japanese Patent Application Publication No. H11-73384 discloses that its object is to provide an information processing device capable of preventing the network propagation of computer viruses by dynamically changing the logical connection and non-connection with the network in an information processing device such as a computer connected to a network, whereby a network connection and non-connection command is issued dynamically to a network connection mechanism based on a network separation program in order to realize the connection and non-connection with the network, and a control signal is sent to the operating system and the virus check program so that the information processing device is set to be in a simulated stand-alone state while the virus check processing is being executed, and the network diffusion of viruses during the virus check processing can thereby be prevented.
Furthermore, Japanese Patent Application Publication No. 2007-265023 discloses an information processing device which includes a network device and is connected to a network via the network device in order to reliably prevent the diffusion of computer viruses on a network, wherein the information processing device comprises a discontinuation processing unit which discontinues the function of the network device based on a disconnection instruction signal for instructing the disconnection from the network, and a setting unit which invalidates the function of the network device and sets the network device to be in a locked state which can only be unlocked by a specific authorized person based on the disconnection instruction signal.